The present specification generally relates to computer disk drives. More particularly, the present specification describes method and apparatus for dampening the vibrations of a disk drive.
Disk drives are used to store information generated by computers. A disk drive includes a head mechanism for transferring data to and from circular or spiral tracks on one or more recording surfaces of the drive; a recording medium, generally including a circular disk or multiple disks; a spindle motor for rotation about an axis perpendicular to a recording surface at the center of the disk; and a hub for rotating the disk.
When a drive, especially a flying head drive, is excited at a disk""s natural frequency, the drive causes unwanted disk vibrations. The effects of the vibrations include wobbling and warping and can cause errors in read out and recording processes, or even malfunction of the disk drive.
Many disk drives utilize dampers to reduce vibrations. Dampers may include spacers, shock absorbers and dampening layers made of absorbing material such as rubber. These dampers offer some damping to attenuate the effects of spindle vibration and environmental shocks. However, many such dampers often cannot provide sufficient damping for disk vibrations, especially for vibrations at the disk""s natural or resonant frequency.
The inventor noticed that disk drives using flying heads and plastic disks are especially sensitive to external vibrations that occur at the disk""s resonant frequency because its resonant frequency falls within the drive""s operating vibration spectrum, e.g. 10 to 400 Hz.
The present disclosure describes method and apparatus for dampening vibrations of a disk drive, especially at the disk""s resonant frequency. The apparatus includes a disk cartridge including a top shell and a bottom shell forming an enclosure. A disk is placed within the enclosure where the gap between the inner surfaces of the top and bottom shells and the disk is sufficiently tight to provide aero damping. The tight gap may be provided radially between disk edge surfaces and inner radial edge surfaces of the top and/or bottom shells to provide aero damping.
In a preferred embodiment, the tight gap covers the entire surface of both sides of the disk. In an alternative embodiment, the tight gap portion is formed by a depression on the top shell covering the disk extending from less than about 25 mm in radius to about 66 mm in radius and about 280 degrees in angle. The size of the depression could be made smaller. In a further alternative embodiment, the depression can also be formed on the bottom shell to provide the tight gap between the bottom surface of the disk and the inner surface of the bottom shell over a portion of the disk.
In a particular embodiment, the drive has a flying head and an optical disk. The disk has a diameter in a range of approximately 120 millimeters to 140 millimeters.
The cartridge includes a shutter that covers the access area. The shutter is movable to uncover the access area to allow the disk drive to access the disk. The cartridge also includes a hub mounted within a central aperture in the disk. The hub rotatably holds and allows the disk drive to spin the disk.
The cartridge system can be used in a near-field recording mode. The system includes an optical data storage disk, a top shell and a bottom shell forming an enclosure with a tight gap, and a shutter that is movable to allow access to the disk. The system also includes a near-field recording head assembly with a solid immersion lens that transmits a beam of radiation to record data on the disk via evanescent coupling.
A method for dampening vibrations of a disk fixed inside a drive is also disclosed. The method includes housing the disk in an enclosure formed.from a top shell and a bottom shell. The damping occurs when the inner surfaces of the top and bottom shells and either or both surfaces of the disk form gaps sufficiently tight to provide aero damping. The damping also occurs when the radial edge surfaces of either or both the top and bottom shells and the radial edge surface of the disk form gaps sufficiently tight to provide aero damping.